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< h1 > Parsec Presentation< / h1 >
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< p > < img src = "http://yogsototh.github.io/parsec-presentation/parsec/img/mp/AST.png" alt = "AST" / > < br / >
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< div class = "intro" >
< p > < span class = "sc" > < abbr title = "Trop long; pas lu" > tlpl< / abbr > : < / span > Une introduction rapide à Parsec. Un parser en Haskell.< / p >
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< li > The < span class = "sc" > < abbr title = "HyperText Markup Language" > html< / abbr > < / span > presentation is < a href = "http://yogsototh.github.io/parsec-presentation/parsec.html" > here< / a > .< / li >
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Parsec
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< author > < em class = "base1" > by< / em > Yann Esposito< / author >
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< p > < twitter > < a href = "http://twitter.com/yogsototh" > < span class = "citation" data-cites = "yogsototh" > @yogsototh< / span > < / a > , < / twitter > < googleplus > < a href = "https://plus.google.com/117858550730178181663" > +yogsototh< / a > < / googleplus > < / p >
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< p > < em class = "base1" > for< / em > < a href = "http://www.meetup.com/riviera-scala-clojure" > Riviera Scala Clojure Meetup (Haskell) < / a > < br / > < em class = "base1" > the< / em > < ti style = "font-size: .8em" > 8 Oct 2013< / ti > < / p >
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< h2 id = "parsing" >
Parsing
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Latin pars (ōrātiōnis), meaning part (of speech).
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< strong > analysing a string of symbols< / strong >
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< strong > formal grammar< / strong > .
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< h2 id = "parsing-in-programming-languages" >
Parsing in Programming Languages
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Complexity:
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Method
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Typical Example
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Output Data Structure
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Splitting
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CSV
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Array, Map
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< tr class = "even" >
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Regexp
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email
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< li > Fixed Layout Tree
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< tr class = "odd" >
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Parser
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Programming language
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< li > Most Data Structure
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< h2 id = "parser-culture" >
Parser < span class = "and" > & < / span > culture
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In Haskell Parser are really easy to use.
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Generally:
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In most languages: < strong > split< / strong > then < strong > regexp< / strong > then < strong > parse< / strong >
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In Haskell: < strong > split< / strong > then < strong > parse< / strong >
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< h2 id = "parsing-example" >
Parsing Example
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From String:
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< pre class = "sourceCode haskell" > < code class = "sourceCode haskell" > (< span class = "dv" > 1< / span > < span class = "fu" > +< / span > < span class = "dv" > 3< / span > )< span class = "fu" > *< / span > (< span class = "dv" > 1< / span > < span class = "fu" > +< / span > < span class = "dv" > 5< / span > < span class = "fu" > +< / span > < span class = "dv" > 9< / span > )< / code > < / pre >
< p >
To data structure:
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< img src = "http://yogsototh.github.io/parsec-presentation/parsec/img/mp/AST.png" alt = "AST" / > < br / >
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Parsec
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Parsec lets you construct parsers by combining high-order Combinators to create larger expressions.
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Combinator parsers are written and used within the same programming language as the rest of the program.
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< p >
The parsers are first-class citizens of the languages […]"
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< p >
< em > < a href = "http://www.haskell.org/haskellwiki/Parsec" > Haskell Wiki< / a > < / em >
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< h2 id = "parser-libraries" >
Parser Libraries
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In reality there are many choices:
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attoparsec
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fast
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Bytestring-lexing
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fast
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Parsec 3
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powerful, nice error reporting
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< section class = "slide" >
< h2 id = "haskell-remarks-1" >
Haskell Remarks (1)
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< p >
spaces are meaningful
< / p >
< pre class = "sourceCode haskell" > < code class = "sourceCode haskell" > f x < span class = "co" > -- ⇔ f(x) in C-like languages< / span >
f x y < span class = "co" > -- ⇔ f(x,y)< / span > < / code > < / pre >
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< section class = "slide" >
< h2 id = "haskell-remarks-2" >
Haskell Remarks (2)
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< p >
Don’ < code > < *> < / code > , < code > < $> < / code > ).< br / > Consider them like separators, typically commas.< br / > They are just here to deal with types.
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< p >
Informally:
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< pre class = "sourceCode haskell" > < code class = "sourceCode haskell" > toto < span class = "fu" > < $> < / span > x < span class = "fu" > < *> < / span > y < span class = "fu" > < *> < / span > z
< span class = "co" > -- ⇔ toto x y z< / span >
< span class = "co" > -- ⇔ toto(x,y,z) in C-like languages< / span > < / code > < / pre >
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< section class = "slide" >
< h2 id = "minimal-parsec-examples" >
Minimal Parsec Examples
< / h2 >
< pre class = "sourceCode haskell" > < code class = "sourceCode haskell" > whitespaces < span class = "fu" > =< / span > many (oneOf < span class = "st" > " \t " < / span > )
number < span class = "fu" > =< / span > many1 digit
symbol < span class = "fu" > =< / span > oneOf < span class = "st" > " !#$%< span class = "and" > & < / span > |*+-/:< => ?@^_~" < / span > < / code > < / pre >
< pre class = "sourceCode haskell" >
< code class = "sourceCode haskell" > < span class = "st" > " \t "< / span > < span class = "co" > – < / span > < span class = "st" > ""< / span > < span class = "co" > – < / span > < span class = "st" > “32”< / span > < span class = "co" > – < / span > < / li >
< / ul > < / li >
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< span class = "co" > –
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Published on 2013-10-09
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